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Tales of the Coast
America's Coasts

Coral Coast

Coral reefs are massive calcareous rock structures that are slowly secreted by simple colonial animals that live as a thin layer on the rock surface. The living organisms continually build new structures on top of old, extending the reefs seaward toward deeper water and upward toward the surface.

The Florida Reef Tract comprises coral reefs along the southeastern edge of the Florida Peninsula in the Atlantic Ocean to the Florida Keys and westward into the Gulf of Mexico. In addition to the reefs themselves, coasts in these areas consist of calcareous beach sediments derived from pulverized corals.

Coral coast are also found throughout the Hawaiian Archipelago. Reefs grow adjacent to the volcanic island and provide beach sediments in a similar fashion to those along the Atlantic and Gulf coral coasts. In the remote and uninhabited Northwestern Hawaiian Islands, one of the world's most undisturbed coral reef ecosystems thrives among the islands and atolls.

Reef-building corals require clear water. The corals need to be free of sediments in order to trap food particles, and their algae require sufficient light for photosynthesis. The upper limit of reef growth is controlled by the level of low tide. Corals cannot stand more than brief exposures out of the water (for example, during the passage of a steep wave trough).

While coral reefs produce rock structure, they also produce calcareous sediments. Waves and currents pulverize coral skeletons into sand-sized particles. However, on many reefs, calcareous algae (Hallemeda sp.) produce a majority of the sediments. The crushed calcareous cells of other animals, such as mollusks, sea urchins and sand dollars, also provide sediment.

Coral coasts are found in the southeastern Atlantic from St. Lucie Inlet to Biscayne National Park in Florida. The coral reefs in this area are an extension of the reef tract that surrounds the southern edge of Florida from the Atlantic into the Gulf of Mexico.

Nearshore coral formations include hardbottom areas and patch reefs, which host octocoral, macroalgae, stony coral and sponges. From Martin County to Palm Beach County, Florida, limestone ridges and terraces have been colonized by reef biota. Mid-shelf and shelf margin reefs are located offshore from Palm Beach County to Miami-Dade County.

Worm reefs are also found in the nearshore waters of southeastern Florida. Worm reefs are a type of biogenic reef, not related to coral reefs, that are produced by colonies of tubeworms, Serpulid worms and Sabellariid worms are two types known to form significant reef structures by constructing external tubes in which they live. The Serpulids build their tubes from calcareous secretions and the Saberllariids by cementing particles of sand and shell fragments around their bodies. Colonies of these worms are capable of constructing massive structures by cementing their tubular structures together.

Live coral reefs surround the Florida Keys in southwestern Florida. Hardbottom habitats in this area feature rock colonized by calcifying algae, octocorals, stony corals and sponges. Patch reefs dominated by stony corals are found near Key Largo, Key West and Elliott Key. Bank reefs, also know as forereefs, extend seaward from other reef types.

Located immediately west of the Florida, the Tortugas Banks are extensive coral reefs growing on a foundation of Pleistocene-era limestone. These reefs have a high degree of coral cover but low coral diversity.

More reef areas are found on the West Florida Shelf in the Gulf of Mexico, extending west and north of the Florida Keys and the peninsula. Pulley Ridge is a rocky underwater feature located west of the Keys that is colonized by a vibrant reef ecosystem. Farther north are the Florida Middle Grounds, which comprise carbonate ledges westward of the bend in Florida's coastline. The Florida Middle Grounds are the northernmost coral reefs in the continental U.S. They support algae, sponges, urchins and many species of coral and fish.

Coral coasts are found throughout the Hawaiian Islands, in both the main part of the archipelago and the remote Northwestern Hawaiian Islands (NWHI). The main Hawaiian Islands feature non-structural reef communities, fringing reefs and two barrier reefs. In addition to hosting corals, fish and other reef biota, these reefs provide substrate for the island beaches when waves pulverize the calcareous reef structures.

The NWHI stretch over 2,000 km westward of the main Hawaiian Islands. This older part of the Hawaiian Archipelago consists of tiny islands, atolls, submerged banks and reefs. The reefs in this region are possibly the healthiest reef ecosystems in the United States. They host over 7,000 species, including many that are rare and endangered. On June 15, 2006, the President of the United States designated nearly 140,000 square miles of the NWHI as a national monument.

 

Coral Coasts

Reefs are of major economic importance to the communities along which they are located. For millennia, coastal peoples have relied on coral reefs as a source of food. Reefs also support tourism, which is now a global industry. An additional benefit of reefs is the shelter from waves that they provide to adjacent shores.

Coral Reefs

One of the critical ecological issues of our times is the rapid degradation of coral reefs around the world by various natural and human activities. The most widespread impacts are water pollution, dredge and fill operations, over-harvesting of fish and shellfish, and the harvesting of some corals for jewelry. Even far from the coast, deforestation, urban sprawl and sloppy agriculture produce vast quantities of sediment and pollution that enter the sea and degrade reefs in the vicinity of river mouths.

Florida's Atlantic Reefs

The reefs along southeastern Florida are the highest latitude reefs in the western Atlantic Ocean. They are located extremely close to the highly developed coastline of this region.

Rare Habitats

Pulley Ridge and the Florida Middle Grounds were each designated as a Habitat of Particular Concern (HAPC) by the Gulf of Mexico South Atlantic Fishery Management Council. An HAPC is a location where the use of potentially damaging fishing equipment, such as bottom trawls, is prohibited, and the removal of coral is limited or banned.

Hawaiian Reefs

In the main Hawaiian Islands, reefs are a vital part of the tourist economy, but they are increasingly threatened by pollution, overfishing, runoff and competition from invasive species.